Removal of chlorides from solutions of amino acids



Patented Oct. 31, 1939 2,178,510

REMOVAL OF CHLORIDES FROM SOLUTIONS OF AMINO ACIDS Louis Gerber, Peoria, 111., assignor, by mesne assignments, to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application June 20, 1938, Serial No. 214,729

2 Claims. (Cl. 260-534) This invention relates to processes for obtainment with the hydrogen chloride gas may be anying amino acids, such as glutamic acid, leucine, Where between 30 and 120 F. The temperature tyrosine, or other amino acid or amino acids, as will be selected so as to avoid temperatures at may be desired, from protein or protein-containwhich the amino acid or acids to be ultimately ing-substance in which the amino acid solution recovered tend to precipitate; temperature, as B at some stage of the process contains an inwell as pI-I (and, of course, the density of the organic chloride or chlorides, for example, sodium solution) being a factor determining solubility chloride, or potassium chloride and/or amor insolubility. monium chloride, the presence of which inter- Preferably the gas treatment is carried out in 30 feres with or makes diificult the isolation and retwo stages, the first at a relatively high temperacovery of the desired amino acid or acids and hire and the second, after removal of precipitated tends to contaminate the product or products a at a lower temperature- The reason for h bt i d, this is that at the higher temperatures there is It is the object of the present invention to e s n e Of p c pitation of amino acids.

provide a simple and eifective method for remov- Most of the chlorides will come out at the higher 18 ing such salts from the amino acid solution. t mp a leaving a Small amount for the Amino acids are produced by the hydrolysis second treatment at the lower temperature, at

of protein substances and it is believed that the which stage the salt is less soluble and more hydrolysis of most vegetable protein substances hydrogen gas absorption can take place.

20 yields some seventeen amino acids. These acids Under ordinary conditions the temperature 20 have difierent solubility characteristics and procduring the first stage will be 100 to 120 F. and esses aiming at the isolation and recovery of any- 70 to 80 F. in the second stage. During these particular amino acid or acids such control so-lutreatments the intention is to keep the solution bility conditions in the solution so that a par as fully saturated with the gas as possible. Under ticular am no a id a y be p e pitated these conditions the time will be from 25 to 35 25 or crystallized while other acid or acids remain minutes in the first tage and from 10 to 15 in solution. The hydrogen ion concentration of minutes in the second stage the solution is a factor determining The treatment hydrogen chloride gas can and as (in the common case of a hydrolysate probe carried on with the liquor t any pH duced by the acid hydrolysis of protein substance) The process f this invention is applicable to PH of the hydrolyzed solutlon i Y the treatment of any solutions of amino acids 2253i? 21 1258 e ii zer i t ir g i i efifi ffgg ggg taining kali metal and/or ammonium chlo- 1 rides. The invention is not limited to treatment m order to raise the pH to the proper level fol of hydrolysates which have been neutralized with prefzipitationpf desired .amino acid alkaline substances but is applicable to any solu- 5 Thls neutralization results in the formation of tion of amino acids containing the before men sodium chloride, for example, if the hydrolyzing acid is hydrochloric acid, and the neutralizing tmned For example, sodllum chlorldehs agent Sodium hydroxide, as is most Common Am such may be 1ntroduced1n an ammo acid solution other salt, ammonium chloride, results from the a after It has Served 113$ P It a h 40 4O combination of the hydrolyzing agent, hydro- S11 ab1e t0 ove thesalt, The invention is pchloric acid, with the ammonia which is produced, phfmble to ammo acld 50111131011? Obtamed m to some extent, in the hydrolyzmg Operation animal as well as vegetable protein substance by If potassium hydroxide were used as a neutraliz- Whatever 'Q may h ing agent, the neutralized solution would con- The followlhg 1S a sphclfic f:Pialflple tr t ng 4 tain potassium chloride. These inorganic chlothe employmeht P the lnvehtloh as a step 1n the rides are objectionable for the reasons stated; process of Obtalnlng mlc acld and/or leucine and the present invention is based upon the disand tyrosine from corn s It will be undercovery that they may be removed by bubbling Stood. however, that this eXample is P y nhydrogen chloride through the amino acid soluformative hd yp a The invention is not 50 tion containing the inorganic chloride or chlot d thls partlcular process I101 t0 the p rides, which, under these conditions, will be preficu a given n the e p The intention is cipitated and may be removed by filtration or by to cover all equivalents of the means and agents other suitable separating operation. Specified and all modifications of the invention The temperature of the liquor during the treatwithin the scope of the appended claims. 55

Exam ner-100 parts, by weight, of starch-free corn gluten is boiled for twenty hours under a reflux condenser with 400 parts of 20% hydrochloric acid. The solution is then cooled to 140 F., centrifuged to remove humin substances and evaporated to a density of Baum. Caustic soda is added in suflicient quantity to raise the hydrogen ion concentration to 6.4 pH. At this temperature and pH the leucine and tyrosine are precipitated and may be removed by filtration.

The filtered solution will contain the sodium salts of the amino acids other than tyrosine and leucine and also sodium chloride and some ammonium chloride.

The liquid is placed in an acid resistant container into which is introduced, through the bottom, a stream of hydrogen chloride gas for minutes with the temperature of the liquor maintained between 100 and 120 F. by means of a cooling coil. The precipitate is then removed by filtration, the filtrate cooled to I0"--80" F. and the hydrogen chloride gas bubbled through the liquid maintained at -80 F. The liquid is then again filtered. This will remove substantially all of the sodium and ammonium chlorides. The amount of salt precipitated from 1500 cc. of liquor, for example, will be about 300 grams, 285 grams of sodium chloride and 15 grams of ammonium chloride. The clarified solution may then be treated in any suitable manner for the production of glutamic acid, for example by the process described and claimed in application for United States patent of J. Paul Bishop, Serial No. 178,428, filed December 6, 1937. The leucinetyrosine precipitate may be treated for the isolation, recovery and refinement of tyrosine and for leucine by any suitable process, for example, by the process described and claimed in the application for United States patent of Louis Gerber, Serial No. 214,730, filed June 20, 1938. These operations form no part of the present invention.

I claim:

1. Method of treating a solution of amino acids containing chlorides of the group consisting of sodium chloride, potassium chloride and ammonium chloride which comprises: passing hydrogen chloride gas through the solution with the solution at a temperature between and F.

2. Method of treating a solution of amino acids containing chlorides of the group consisting of sodium chloride, potassium chloride and ammonium chloride which comprises: passing hydrogen chloride gas through the solution with the solution at about l00-120 F.; removing the precipitate; repeating the gas treatment with the solution about 70-80 F., and removing the precipitate.

LOUIS GERBER. 

